A silvery-white, malleable, ductile, metallic rare-earth element obtained from monazite and bastnaesite and used in improving high-temperature characteristics of iron, chromium, and related alloys. Atomic number 64; atomic weight 157.25; melting point 1,312°C; boiling point approximately 3,000°C; specific gravity from 7.8 to 7.896; valence 3. See Table at element.
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.